The main goal of a raw sugar refinery is to economically convert raw sugar into a safe and marketable product for human consumption. Numerous and varied unit processes are utilized to achieve this goal. Crystallization is one of these major unit processes.
The typical refinery treats purified fine/white liquor with several crystallization “strikes” that produce a combined saleable product. Due to the recovery/removal of sugar out of the fine liquor feed, the non-sucrose impurities increase in concentration in the strike run-off syrups. As a result, production of final product quality sugar via crystallization becomes cost ineffective. The residual run-off syrup (also referred to as residual refined syrup) sucrose content is relatively high and without further sugar recovery, results in significant sugar recovery income losses.
The traditional process to reduce the sugar losses in the residual run-off syrup utilizes a recovery house. The recovery house basically utilizes crystallization in order to produce an acceptable raw sugar quality that is fed back into the raw sugar melter unit of the refinery. There are numerous techniques utilized in recovery house designs, but all utilize the energy and the equipment intensive process of evaporative crystallization and centrifugation.